Single phase delivery articles for active agents which release such agents by diffusion, by erosion or dissolution, or by combustion, for example, are well known. Examples include candles comprising fragrance components dissolved or dispersed in the wax and released by burning the candle and toilet bowl or urinal blocks which release fragrance, antimicrobials, colorants, and/or bleaches as the block is slowly dissolved. In this context, such articles will be considered single phase if the active agent is dispersed or dissolved uniformly throughout the bulk of the article. While minor inhomogeneities may be present in the continuous matrix of known articles, these inhomogeneities do not generally materially affect the active loading capacities of the articles.
In such articles, the mechanical properties of the finished article are frequently compromised by the presence of the active agent or agents within a single phase matrix, as defined herein. In the case where the active comprises an insoluble liquid dispersed uniformly throughout the solid matrix, the mechanical properties of the composite article may often be approximated by the volume weighted average of the properties of the matrix material and the corresponding properties of the liquid agent. This places a severe upper limitation on the total amount of liquid agents which may be incorporated without loss of rigidity in the finished article. In addition, the incorporation of large amounts of an incompatible agent may result in blooming or sweating of the agent at the surface of the article.